Hi @Kiwart 
Sorry for getting back to you a bit late — I hope all is well with you
After reviewing your requirements, I think Easify Box Bundle Builder BYOB could be a great fit for the type of bundle experience you’re looking to create.
I’ve created a similar demo to help you better visualize how it works:
To get started, you can create a new bundle and choose the Predefined Box Sizes box type. This setup works particularly well for scenarios like yours, where customers first choose a bundle size before selecting the products they’d like to include.
For example, to create options such as Single Pack, Double Pack, and Triple Pack, you can simply go to the Discount & Subscription section and configure your Box Size Options based on the number of products you want each bundle to contain. This gives customers a clear and intuitive way to choose the package that best suits their needs.
Next, you can add the collections or specific products that customers will be allowed to choose from. Once a customer selects a Double Pack or Triple Pack, they’ll be able to build their own bundle by choosing their preferred products directly within the bundle-building flow.
If you’d also like customers to choose variants such as color, size, or MacBook model, you simply need to create those variants in Shopify beforehand, and the app will allow customers to select them during the bundle creation process.
Overall, if your goal is to offer a modern, visually appealing bundle builder where customers can choose between Single, Double, or Triple Packs and then build their own bundle with the products they want, Easify Box Bundle Builder (BYOB) is definitely worth exploring. 